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Appendix I.

751

P. 230. Turning Eccentric Sheave.Where much of
this work is to be done, and where the eccentricity of the sheaves
to be turned varies much, the mandrel shewn at Fig. 737 is an
ingenious and useful appliance. B is an expanding mandrel,
having a cone A and four inclined keys D D that can be advanced
outward or inward by the nut G, so as to grip the sheave firmly.
The eccentricity may be adjusted by applying the handle H to
the screw at B, and by unloosing and refastening the nut F. The
whole is placed in the lathe by bolting the frame c to the face
plate j, then advancing the poppet head to the centre F.

. 737.

P. 232. Boring Eccentric Straps.Instead of turning
the straps in the lathe a heavy drilling machine may be con-
veniently adapted for boring, purposes, as in Fig. 738. A large
cutter c is placed horizontally through a slot in the boring bar F
(or drilling machine spindle), and the radial feed may be obtained
by giving a slight turn to the pinion D, which fits into teeth upon
the cutter. B shews the eccentric straps, which are firmly bolted
to the table A.

P. 232. Planing Eccentric Straps.The method shewn
at EJ, Fig. 245, may be varied by using a shaping machine and